Ecophysiological mechanisms characterizing fen and bog species: Focus on variations in nitrogen uptake traits under different soil-water pH
Ecophysiological mechanisms characterizing fen and bog species: Focus on variations in nitrogen uptake traits under different soil-water pH
复制标题
沼泽和沼泽物种的生态生理机制：关注不同土壤-水 pH 值下氮吸收性状的变化
DOI：
10.1007/s00442-011-2161-3
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发表时间：
2012
期刊：
影响因子：
2.7
通讯作者：
Nakamura Takatoshi & Nakamura Motoka
中科院分区：
文献类型：
--
作者：
Nakamura;M.;Nakamura;T.;Tsuchiya;T.;Noguchi;K.;Nakamura Takatoshi & Nakamura Motoka
沼泽植物的生产力和氮素利用特征在沼泽和沼泽之间存在显著差异，但土壤N丰富度并不一定不同，而沼泽的土壤-水pH值明显低于沼泽。这些关系背后的生理生态机制尚不清楚。为了评估氮素形态的相对有效性与土壤-水pH的关系，我们重点研究了单位根重净氮素吸收率（NNUR）、谷氨酰胺合成酶活性和硝酸盐还原酶活性，并在完整的生境中对毛草（Carex lyngbyei）和沼泽（C. middendorffii）的幼苗进行了交互移植实验。沼泽样地土壤-水pH值明显较低，但NH4+、NO3−和溶解有机氮浓度在沼泽样地和沼泽样地之间无显著差异。两种酶的无机氮同化活性在不同位置和物种间没有差异。然而，生长在沼泽地的沼泽物种的NNUR急剧下降，表明有机氮的吸收受到抑制。不同地点间沼泽物种的NNUR差异不显著。这些结果表明，无机氮有效性在两种生境之间没有差异，但有机氮有效性在低ph沼泽中降低，特别是在沼泽物种中。因此，即使在相似的N丰富度下，N形态的相对有效性也表现出依赖于根区土壤-水pH值差异的物种特异性变化，这将在与沼泽梯度相关的植物分布策略中发挥关键作用。
Although the productivity and nitrogen (N)-use traits of mire plants differ dramatically between fens and bogs, soil N richness does not necessarily differ, whereas the soil–water pH is distinctly lower in bogs than in fens. The ecophysiological mechanisms underlying these relations are unclear. To assess the relative availability of N forms in relation to soil–water pH, we focused on the net N uptake rate per unit root weight (NNUR), glutamine synthetase activity and nitrate reductase activity, and performed reciprocal transplant experiments with the seedlings of fen (Carex lyngbyei) and bog (C. middendorffii) sedge species in intact habitat sites. The soil–water pH was clearly lower at the bog site, but the NH4+, NO3−or dissolved organic-N concentrations did not differ between the fen and bog sites. The activity of both enzymes for inorganic-N assimilation did not differ among the sites and species. However, the fen species grown at bog sites showed a drastic decrease in the NNUR, suggesting a suppression of organic-N uptake. The bog species showed no NNUR difference between the sites. These results indicate that inorganic-N availability does not differ between the two habitats, but organic-N availability is lowered in a low-pH bog, particularly in the case of fen species. Therefore, the relative availability of N forms shows species-specific variations that depend on the differences in the soil–water pH of root zone, even at similar N richness, which would play a key role in plant distribution strategies in relation to the fen-bog gradient.